Quantitative growth hormone secretion and final adult height

OBJECTIVE The relationship of quantitative GH secretion to height, growth velocity and puberty is complex and has been the subject of extensive study in children. This study was designed to relate quantitative GH secretion to final height, SUBJECTS Twenty tall (>183cm, 90th centile for adult height) and 20 short (<166cm, 10th centile) postpubertal men who had recently completed linear growth (age range 18-27 years). MEASUREMENTS GH dynamics were studied on four occasions; insulin (0.15 units/kg, iv)-induced hypoglycaemia and GHRH (100 mg, iv) with and without the anticholinesterase, pyridostigmine (120 mg orally). Spontaneous nocturnal GH secretion was assessed by 20 minute sampling from 2100h until 0600h, GH was measured by IRMA. Analysis was by comparison of peak GH response and area under the curve (AUC), GH profiles were further analysed using the 'pulsar' programme. RESULTS The mean height in the tall group was 187.7cm (range 183-197) compared to 163.5cm (range 160-166) for the short group. No difference existed between groups in the GH response to hypoglycaemia or GHRH with and without pyridostigmine, Area under the curve, pulse number, length and amplitude for spontaneous nocturnal GH secretion showed no significant difference between the tall and short subjects. Serum IGF-1 (mean 230.5 +/- 15.4 vs. 230.6 +/- 18.9 mu g/l) did not differ between the groups. CONCLUSIONS Quantitative GH secretion does not appear to be an important determinant of final height in healthy individuals.